DITTANDER

BROAD-LEAVED PEPPERWORT

Lepidium latifolium

Cabbage Family [Brassicaceae]

month8jul month8july month8aug

status
statusZnative
flower
flower8white
inner
inner8yellow
morph
morph8actino
petals
petalsZ4
type
typeZglobed
type
typeZpanicle
stem
stem8round
rarity
rarityZscarce

25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
A pepperwort which grows on damp bare ground near the sea.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Grows up to 1.5m high and has greyish green waxy leaves.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
A hairless branched plant with many panicles of very small white flowers in rounded clumps at the ends of stalks.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
The globes of white flowers are about a centimetre across.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Un-opened flower buds are tiny, just a millimetre across.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Opened flowers are very small and only about 3mm across.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
The books say it is hairless, but are patently wrong, the stems are greyish due to a thin mat of very short white hairs. Upper leaves/bracts are very narrow lanceolate.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Flowers white with four petals and four white stamens protruding beyond the flower tipped with yellow-pollened anthers.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Stamens protrude well beyond the petals.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Each flower is on a longish thin flower-stalk. Over a dozen such stalks emerge from a radiant point at the end of a stem. Un-upened flower buds have four beetroot-coloured sepals which are not large enough to fully conceal the white petals yet to emerge. The sepals have a few much longer thin white hairs.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Half way up the plant the lanceolate leaves are broader and larger compared to the upper leaves which are relatively much narrower.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
The plant has a greyish-green appearance.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Lowest leaves have a prominent whiter central rib, are larger still and have small teeth.


25th July 2013, Roose, Furness Peninsula, Cumbria. Photo: © RWD
Stems almost white-green near ground level. Lowest leaves are reminiscent of those on Prickly Lettuce but lack auricles or spines along the underside of the rib. The leaves are on short V-shaped stalks.


Not to be semantically confused with : Dill (Anethum graveolens) [an Umbellifer (Apiaceae) with similar name used as a herb in cooking]

Many similarities to : Hoary Cress (Lepidium draba) but that has leaves with fewer larger teeth, the upper leaves have auricles extending backwards each side of the stem. The flower clusters larger and more open with the flowers themselves twice as large at 5-6mm.

It is a much-branched, tall greyish-green plant with panicles of tiny white flowers in small globular clusters at the ends of each termination. Lower leaves are larger and have small teeth, uppermost leaves/bracts narrow lanceolate and much shorter. It is perennial with rhizhomatous roots which spread to form great swathes in damp places near the sea and/or near the riparian zone of riverbanks and streams.

In some parts of the World this is a controlled weed (such as Tasmania). Even in the UK it can spread rather uncontrollably.

The roots of Dittander are able to tap water at considerable depth because the extensive root system reaches down up to 2 metres. Because Dittander prefers a seaside location, it is thus exposed to halogens in the soil which may have arrived by past sea-inundations, for example from large storm surges, large tides, or from tsunamis which are not unknown in the UK. And because the roots reach 2m down, they may already have reached the halocline beneath the soil surface which, near the sea, sits just below the average level of the sea water. In uptaking water Dittander absorbs the halogenated compounds, mainly sodium chloride and sodium bromide. Dittander would rather get rid of excess chlorine and bromine and does so by emitting Methyl Chloride, CH3Cl and Methyl Bromide CH3Br with maximum emissions occurring at midday in the sunshine, exceeded only by the peak emissions at senescence of the plant. It is a major source of these methyl halides, which are partly responsible for the catalytic destruction of ozone in the upper atmosphere. When an ozone hole is created at the poles of the Earth, dangerous amounts of ultraviolet light from the sun is allowed onto the Earths surface.

The glucosinolate Sinigrin is present in large amounts, which is the source of the mustard oils and other sulfur-containing compounds found in Dittander. The main volatile components of the seed and roots of Dittander comprise Allyl-Isothiocyanate, Benzyl-Isothiocyanate, Sec-Butylsothiocyanate, whilst the leaves contain Allyl-Isothiocyanate and 1-Cyano-2,3-EpiThioPropane as the main volatiles.

The leaves have a very bitter and peppery taste (due to the poisonous Glucosinolates present) which only become edible after extensive boiling and soaking, so, in the UK, are not worth the considerable effort required.


  Lepidium latifolium  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae

 BSBI maps
genus8Lepidium
Lepidium
(Pepperworts)

DITTANDER

BROAD-LEAVED PEPPERWORT

Lepidium latifolium

Cabbage Family [Brassicaceae]